title: In vitro demineralization of tooth enamel subjected to two whitening regimens.
abstract: BACKGROUND
  The resistance of bleached enamel to demineralization has not been elucidated fully. In this study, the authors aimed to examine the level of in vitro demineralization of human tooth enamel after bleaching by using two common bleaching regimens: home bleaching (HB) and office bleaching (OB) with photoirradiation.
  
  
  METHODS
  The authors bleached teeth to equivalent levels by means of the two bleaching regimens. They used fluorescence spectroscopy to measure the reduction in enamel density and the release of calcium into solution after storing the treated teeth in a demineralizing solution for two weeks. They also visualized and quantified mineral distribution in demineralized bleached enamel over time by using a desktop microcomputed-tomographic analyzer.
  
  
  RESULTS
  Enamel subjected to HB or to photoirradiation without bleaching showed increased demineralization. In contrast, enamel treated with OB was more resistant to demineralization. This resistance to demineralization in teeth treated with OB presumably is due to peroxide's permeating to deeper layers of enamel before being activated by photoirradiation, which enhances mineralization.
  
  
  CONCLUSIONS
  The mineral distribution pattern of enamel after treatment plays a critical role in providing resistance to demineralization in whitened teeth.
  
  
  CONCLUSIONS
  OB confers to enamel significant resistance to in vitro demineralization. Dentists should supervise the nightguard HB process.
authors.affiliation: Department of Clinical Cariology, School of Dentistry, Showa University, Tokyo, Japan.
authors.forename: Kayoko
authors.initials: K
authors.lastname: Ogura
authors.forename: Reina
authors.initials: R
authors.lastname: Tanaka
authors.forename: Yo
authors.initials: Y
authors.lastname: Shibata
authors.forename: Takashi
authors.initials: T
authors.lastname: Miyazaki
authors.forename: Hisashi
authors.initials: H
authors.lastname: Hisamitsu
mesh_terms: D002118:Calcium / Q000032:analysis; D000077463:Carbamide Peroxide; D003116:Color; D003743:Dental Enamel / Q000187:drug effects* / Q000648:ultrastructure; D006801:Humans; D006861:Hydrogen Peroxide / Q000627:therapeutic use; D008903:Minerals / Q000032:analysis; D010545:Peroxides / Q000627:therapeutic use; D010789:Phototherapy / Q000295:instrumentation / Q000379:methods; D012464:Saliva, Artificial / Q000737:chemistry; D013050:Spectrometry, Fluorescence / Q000379:methods; D013696:Temperature; D014073:Tooth Bleaching / Q000379:methods*; D058205:Tooth Bleaching Agents / Q000627:therapeutic use*; D017001:Tooth Demineralization / Q000209:etiology* / Q000503:physiopathology; D014508:Urea / Q000031:analogs & derivatives / Q000627:therapeutic use; D055114:X-Ray Microtomography / Q000295:instrumentation
chemical_list: D008903:Minerals; D010545:Peroxides; D012464:Saliva, Artificial; D058205:Tooth Bleaching Agents; D000077463:Carbamide Peroxide; D014508:Urea; D006861:Hydrogen Peroxide; D002118:Calcium
keywords: Tooth; bleach; demineralization; enamel; fluorescence spectroscopy; microcomputed tomography